Woven fabric for safety belts of high energy-absorbency

ABSTRACT

A safety belt web is a woven fabric band including nylon warp threads and warp threads of lesser elongation than the nylon threads, the nylon warp threads being disposed outside the low elongation warp threads so that the latter is unexposed and the low elongation threads are under tension in the relaxed web and advantageously linear. The elongation properties and amount of low elongation warp threads are such that their maximum elongation does not exceed 20 percent, at a total web tension of about 500 kilograms. In one form of the belt web, top and bottom sets of warps and a filler which alternately interweaves successive upper and lower warp groups form top and bottom woven webs, the longitudinal lines of the filler transfer points dividing the space between the upper and lower webs into longitudinal passageways along which extend core threads of less elongation and less weave crimp than the warps. The core threads may be formed of similar filaments or of filaments having different elongation to load characteristics and are preferably linear.

iliiite States aterit 91 'llaltada 1 1 Mar. 25, 1975 i 1 WOVEN FABRHCFOR SAFETY BELTS O11 HIGH ENERGY-ABSORBENCY [63] Continuation-impart ofSer. No. 78,774, Oct. 7,

1970, abandoned.

Taliezo Takada, I-likone, Japan [30] Foreign Application Priority DataJan. 2, 1972 Japan 474480 [52] US. Cl. 139/383 R, 139/415, 139/426 R[51] Int. Cl. D0301 15/00, D03d 11/00 [58] Field 611 Search 139/383 R,420 R, 426 R, 139/408-4l5; 280/150 SB; 297/385 [56] References CitedUNITED STATES PATENTS 2,471,166 5/1949 Neff 139/383 2,788,023 4/1957Renaud 139/410 2,794,450 6/1957 Gatzke 139/411 3,148,710 9/1964 Riegeret al. 139/415 3,296,062 1/1967 Truslow 139/426 X 3,322,163 5/1967Hughes v 139/383 3,446,252 5/1969 Maxham.... 139/420 3,464,459 9/1969Ballard 139/383 3,530,904 9/1970 Ballard t t 139/383 3,537,488 11/1970Le Boeuf... 139/415 3,550,956 12/1970 Lowe 297/385 3,823,748 7/1974Allman et a1. 139/383 R FOREIGN PATENTS OR APPLICATIONS 954,586 4/1964United Kingdom 297/385 990,331 4/1965 United Kingdom 297/385 OTHERPUBLICATIONS 1,180,689 l0291964 German application (Hemesath) 139-420.

Primary Examiner-James Kee Chi Attorney, Agent, or FirmWolder & Gross[57] ABSTRACT A safety belt web is a woven fabric band including nylonwarp threads and warp threads of lesser elongation than the nylonthreads, the nylon warp threads being disposed outside the lowelongation warp threads so that the latter is unexposed and the lowelongation threads are under tension in the relaxed web andadvantageously linear. The elongation properties and amount of lowelongation warp threads are such that their maximum elongation does notexceed 20 percent, at a total web tension of about 500 kilograms.

In one form of the belt web, top and bottom sets of warps and a fillerwhich alternately interweaves successive upper and lower warp groupsform top and bottom woven webs, the longitudinal lines of the fillertransfer points dividing the space between the upper and lower webs intolongitudinal passageways along which extend core threads of lesselongation and less weave crimp than the warps. The core threads may beformed of similar filaments or of filaments having different elongationto load characteristics and are preferably linear.

12 Claims, 7 Drawing Figures I I i 250- I I I I 1 I I l I l W 5 lo a 50a5 [40A/g47/0A/ INVENTOR 7 7K520 739K40 BY MAM/W ATTORNEY WOVEN FABRICFOR SAFETY BELTS OIF HIGH ENERGY-ABSORBENCY REFERENCE TO RELATEDAPPLICATION The present application is a continuation-in-part ofcopending application Ser. No. 78,774, filed Oct. 7, 1970, nowabandoned.

BACKGROUND OF THE INVENTION The present invention relates generally toimprove ments in woven belts, webs, bands and the like and it relatesmore particularly to an improved high energy absorbing web whichishighly useful in safety belts such as vehicle shoulder belts and ischaracterized in decelerating and restraining a passenger in an optimummanner attendent to the rapid deceleration of a vehicle.

Vehicle safety belts are generally employed for securing a passengersbody to the vehicle seat in-a manner to protect the passenger againstany sharp impact and excessive shock consequent to traffic. accidentsand these belts must not only be strong enough so as not to ruptureunder high stress and shock conditions but must be capable of someelastic stretch as well as some non-elastic or non-recoverableextension. If the safety belt possesses very low elongation or has goodelongation recovery due to its high resiliency or fast elastic recovery,it is not suitable for protecting or restraining the passenger againststrong shocks consequent to a vehicle collision.

Vehicle safety belts are generally of twotypes, one being the waist typesafety belt which extends across the passengers waist and the otherbeing the shoulder type safety belt which extends diagonally across thepassengers torso, crossing from one shoulder to the waist and functionsto prevent the upper part of the passengers body from moving or swingingforwardly and downwardly. In the shoulder type safety belt it isparticularly important that the belt be capable of absorbing a highamount of energy within a certain nonrecoverable or non-elasticelongation of the shoulder belt. It has been heretofore proposed toemploy in shoulder safety belts. belts woven of undrawn synthetic fibersor synthetic fibers which have been heat shrunk after the drawingthereof, but such belts do not possess the optimum properties for use asshoulder safety belts. Where the belts are formed of nylon theelongation versus load characteristics as shown in FIG. 3 of thedrawings, are of such values that the energy absorption within asuitable elongation range is insufficient. On the other hand, with abelt formed of polyester fibers, the load required for the desired beltelongation, as shown in FIG. 4 of the drawings, is excessive so as toimpart excessive shock to the passenger. Accordingly, the shouldersafety belt structures heretofore employed and proposed possess numerousdrawbacks and disadvantages and leave much to be desired.

SUMMARY OF THE INVENTION It is a principal object of the presentinvention to provide an improved web or the like.

Another object of the present invention is to provide an improved wovenweb for shoulder type vehicle safety belts.

A further object ofthe present invention is to provide a web of theabove nature which is highly energy absorbant during its initialnon-recoverable elongation and may thereafter be subjected torecoverable or elastic elongation and which is strong, flexible andhighly versatile.

The above and other objects of the present invention will becomeapparent from a reading of the following description taken inconjunction with the accompanying drawings which illustrate preferredembodiments thereof.

In general, theoptimum elongation versus load properties of a webemployed in a shoulder type vehicle safety belt are of the natureillustrated in FIG. 5 of the drawing and is characterized by littleelongation during the initial or early loading, followed by furtherelongation upon reaching a predetermined load or stresswithout anyadditional loading, as shown by that part of the curve enclosed withinthe area delineated by broken lines. The distance between the carwindshield and the passengers head varies somewhat depending on the typeof car but generally averages about 50 centimeters in the medium sizecar, and the distance between the drivers chest and the steering wheelor column is generally about 30 centimeters. In order to minimize orprevent sharp impact between the passenger and the windshield andsteering wheel it is highly desirable that the elongation of theshoulder strap be less than 20 percent under a load of 500 kilograms orsomewhat less. This shock is advantageously absorbed by the safety beltby a substantially non-recoverable elongation and represents the beltenergy absorption which is not thereafter released in any manner whichmay injure the passenger. Thereafter any additional loading on the beltresults in an elastic recoverable elongation thereof.

In accordance with the present invention the optimum elongation versusload characteristics of the vehicle safety. belt is achieved byemploying for the belt a web which includes longitudinally extendingyarns or threads having different elongation versus loadcharacteristics, the amount of the respective threads employed beingsuch as to provide the general characteristics shown in FIG. 5. The webis preferably woven as a band in any known manner, the longitudinalthreads being the warp threads which are interconnected by transversefiller or weft threads. Advantageously the low elongation warp threads,which may likewise have diffferent elongation versus loadcharacteristics less than that of the nylon warp threads may be formedof polyester, polyvinyl alcohol, metal wire or the like or combinationsthereof. The thread or yarns may be monofilaments or continuous filamentor staple fiber single or multiple ply yarns. The low elongation warp orcore threads may include threads of the same type and with the sameelongation or threads of two or more types which may have differentelongation versus load values. Moreover each of the core threads may beformed of filaments having different elongation values.

The web is woven so that the core or low elongation warp threads areunexposed, the nylon warp threads extending along the outer faces of theweb. Moreover, the web construction and weaving is such that in itsrelaxed state the low elongation warp threads are advantageously undertension or less relaxed as compared to the high elongation threads sothat upon loading of the web the low elongation threads are immediatelystressed. In addition, the low elongation warp or core threads approachor are substantially linear in the unloaded web and possess relativelylittle weave crimp. On the other hand, the high elongation warp threadsare relatively highly undulate possessing a relatively high weave crimpso as not to be stressed more than the low elongation warp threadsduring initial web elongation. The web may be of either single or doubleweave construction and in the latter case the low elongation warpthreads are disposed inside the nylon warp in a greater curvature thanthe weave loop of the warp so as to diminish weave shrinkage. In the webdouble weave construction the low elongation warp threads extend throughthe hollow core of the double weave. A weave structure of greatadvantage includes vertically spaced upper and lower warps and a fillerinterweaving alternate successive upper and lower warp groups,transferring between the upper and lower warps to form upper and lowerwoven webs which delineate with the filler along the lines of transferbetween the upper and lower webs longitudinal passageways along whichthe core yarns extend.

The improved safety belt web overcomes the drawbacks and disadvantagesof the webs heretofore employed and proposed, possessing the optimumelongation versus loading and energy absorption characteristics andbeing strong and highly versatile and adaptable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview ofa woven web embodying the present invention;

FIG. 2 is a longitudinal diagramatic sectional view of anotherembodiment thereof;

FIG. 3 is a load versus elongation graph of a nylon fiber belt;

, FIG. 4 is a load versus elongation graph of a polyester fiber belt;

FIG. 5 is a load versus elongation graph of a belt constructed inaccordance with the present invention;

FIG. 6 is a fragmentary longitudinal sectional view of anotherembodiment of the present invention; and

FIG. 7 is a fragmentary transverse sectional view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingsand particularly FIG. 1 thereof which illustrates a preferred embodimentof the present invention, the improved belt comprises a woven fabric webof single weave construction including longitudinally extending nylonwarp threads 1 which define the high elongation warp threads,longitudinally extending low elongation warp threads 3, which may beformed of polyester fibers, polyvinyl alcohol fibers, cotton fibers orthe like or combinations thereof and filler of weft threads 2 of anydesired material interwoven with the warp threads 1 and 3 in the patternillustrated or in any other desired pattern. The nylon warp threads 1are disposed along the outer faces of the web and the warp threads 3underly the warp threads 1 and are unexposed at the web faces. The ratioof the number of nylon warp threads 1 to the number of warp threads 3depends on the denier or thickness of the respective threads and thecomposition of the latter as well as specific elongation load propertiesdesired. For example the warp threads may be equal in number and or inany appropriate alternate number. Moreover, the low elongation warpthreads 3 may be alike or they may be different, for example alternatewarp threads 3 may be of polyester and polyvinyl fibers respectively oreach of the warp threads 3 may be a combination of fibers of differentelongations, for example polyester and polyvinyl alcohol fibers wherebyupon elongation of the web the polyvinyl alcohol fibers are first brokenfollowed by the breaking of the polyester fibers resulting in theabsorption of kinetic energy. With the longitudinal elongation of theweb in the warp direction consequent to application of a shock stressthereto, the lower elongation warp threads are first broken due to theirlow elasticity and extensibility and the small weave shrinkage therebyabsorbing the passengers kinetic energy upon sudden stopping of thevehicle and the nylon warp threads are then elongated due to thepassengers remaining kinetic energy.

As a specific example of a belt web of the construction described aboveand illustrated in FIG. 1 the warp threads 1 and the filler or Weftthread 2 were both twisted nylon filament yarns of 205 filaments of 840denier/2 ply. The warp threads 3 were twisted polyester yarn of 45filaments of 250 denier/4 ply and twisted polyvinyl alcohol yarn of 27filaments of IZOO/denier/l ply and were woven under greater tension thanwarp threads 1 to produce the web construction illustrated in FIG. 1. Asafety belt produced from the aforesaid web exhibited theload-elongation curve shown in FIG. 5. This load-elongationcharacteristic is optimum since the work amount, that the energyrequired for elongation at a specified load, up to 20 percent elongationis very large and is at a load a little less than 500 kilograms, suchenergy corresponding to the area delineated by the elongation-loadcurve, the abscissa axis and the broken vertical line at the 20 percentelongation point. The load-elongated curve of the improved belt web, asillustrated in FIG. 5, demonstrates that in the initial or earlyloading, the combined properties of the nylon, polyester and polyvinylalcohol fibers are first effective, after the rupture of the polyvinylalcohol fibers, the belt web operation depends on the combination of thepolyester and nylon fiber properties and after the rupture of thepolyester fibers the loadelongation curve of the belt web issubstantially the same as that of a nylon belt web, by which time theabsorption of a great amount of the passengers kinetic energy isachieved. It is clear from a comparison of the curves of FIGS. 3, 4 and5 that the work amount characteristics of the improved safety belt isfar superior to those of nylon or polyester alone.

In FIG. 2 there is illustrated another embodiment of the presentinvention in which the improved safety belt is a woven fabric web ofdouble weave construction. The woven web comprises nylon warp threads11, any suitable yarn filler thread 12, and longitudinal threads 13 oflower elongation than the nylon warp threads 11, such as yarns formed ofpolyester fibers, polyvinyl alcohol fibers, cotton or the like, woveninto the inner hollow core of the web. The web is woven in the knownmanner in the pattern shown in FIG. 2. The relationship between threads11 and 13 and their conditions and properties are similar to thesebetween threads 1 and 3 of the first described embodiment and theoperation of the safety belt web is like that illustrated in FIG. 1.

Referring now to FIGS. 6 and 7 of the drawings which illustrate anotherembodiment of the present invention the reference numeral 20 designatesthe improved belt which includes woven top and bottom webs 21 and 22respectively which are formed with a-common single weft or filler 24.The top web 21 is formed of transversely spaced longitudinally extendingundulating yarns 26 interwoven with filler 24 and the bottom web isformed of transversely spaced longitudinally extending undulating yarns27 interwoven with filler 24, the adjacent outer edges of the webs 21and 22 being interconnected by short side webs or edges 28 formed offiller 24 interwoven with side warps 29.

The filler 24 along with the width of the belt and along each transversepass of the tiller 24 alternately transfers between the top and bottomwebs 21 and 22 at regularly spaced intervals, the point of transfer ofthe filler 24 at successive passes being longitudinally aligned toprovide regularly spaced longitudinally extending partitions 30 todelineate with upper and lower webs 21 and 22 longitudinally extendingside-by-side separate hollow passageways 32. While in the illustratedembodiment the interval separating successive filler transfer points isshown as five warps it should be understood that the interval mayinclude a plurality of more or less than five warps.

Enclosed within and extending for the length of each passageway 32 are aplurality of core yarns or threads 33 which are of less weave crimp thanwarp yarns 26 and 27 and are advantageously parallel and linear and maybe under some tension in the relaxed state of the belt 20. The coreyarns 33 have less elongation than the warps 26 and 27 and possess thecharacteristics and relationship to the warps as described in connectionwith warp threads 3 and 13 of the earlier described embodiments and asrelated to warps l and 11.

In operation, the low elongation core threads are first ruptured undersufficient tension due to their low elongation and low weave crimp, butbefore rupture, the core threads neck out or elongate under apredetermined constant load, whereby to absorb a corresponding amount ofkinetic energy which is imparted thereto by the belt restrainedpassenger upon receiving a sharp forward impact force relative to thevehicle. Upon rupture of the core threads the warp threads are elongatedby the passengers remaining kinetic energy.

In accordance with a specific example ofa belt of the structure lastdescribed and shown in FIGS. 6 and 7, the total number of warp threadswas 190, each warp being a 1680 denier twisted nylon filament yarn withthe filler being of the same nylon yarn. The core yarns consisted of 45.pieces of 250 denier, twisted 4 ply polyester filaments and 27 piecesof 1200 denier twisted single ply vinylon filaments, the core yarn beingunder greater tension during weaving than the warp yarns to obtain theillustrated weave structure. The core yarns are equally distributedamong the passageways 32, that is where nine passageways are providedeach contains five pieces of the polyester yarn and three pieces of thevinylon yarn.

With the above belt, at up to 20 percent elongation. the response of thebelt closely approximated the ideal, as earlier described. This is dueto the fact that in the initial loading phase the response is due to thecombined state of the nylon, polyester and vinylon yarns and after thevinylon core threads are ruptured, the load-elongation characteristicsof the combined nylon and polyester yarns control the belt response, andafter the rupture of the polyester yarns, the belt reacts in the mannerof a nylon belt and the ideal overall response is thus achieved.

As explained above, the improved safety belt web possesses excellentoperating characteristics by reason of its load-elongation relationship,which is achieved by the use of the high elongation warp threads, thatis nylon, interposed with and extending along the direction of the lowelongation warp threads for example of polyester fiber, polyvinylalcohol fibers metallic wire, cotton or the like and combinationsthereof. In the early belt loading the ratio of elongation to load isrelatively low as compared to the corresponding ratio of a belt of onlynylon, and then there is an area of further elongation without increasedloading thereby resulting in a high absorption of the passengers kineticenergy with a large work amount and a large work ratio, that is theratio of belt absorbed energy to the energy required to elongate thebelt at the particular loading. Accordingly, the improved safety belt iscapable of protecting the passenger from high energy impact with thevehicle windshield and steering wheel, and is particularly useful forshoulder type safety belts.

While there have been described and illustrated preferred embodiments ofthe present invention, it is apparent that numerous alterations,omissions and additions may be made without departing from the spiritthereof.

I claim:

1. A woven energy absorbing safety belt web comprising first and secondgroups of warp threads of relatively low and relatively high elongationrespectively, and a filler thread interwoven with said warp threads,said second group warp threads having a weave crimp exceeding that ofsaid first group warp threads and said first group warp threadscomprising a plurality of core threads having elongations different fromeach other and lower than that of said second group warp threads, andsaid first group warp threads having a nonrecoverable extensibilityunder a substantially constant predetermined load for a predeterminedelongation before the rupture of said first group warp threads ofmaximum elongation.

2. The safety belt web of claim 1 wherein said second relatively highelongation warp threads are disposed outwardly of said first lowelongation warp threads relative to the opposite outer faces of saidweb.

3. The safety belt web of claim 1 wherein said first warp threads areunder tension relative to said second warp threads when said web is inan overall relaxed condition.

4. The safety belt web of claim 1 wherein said first warp threads ofmaximum elongation extends substantially linearly between said fillerthreads disposed along opposite sides of said first warp threads andsaid second warp threads interweave said filler threads and are disposedalong opposite faces of said web.

5. The safety belt web of claim I wherein said first threads have arupture elongation of 20 percent and at a total load on said web ofabout 500 kilograms.

6. The safety belt web of claim 1 wherein said second threads comprisenylon.

7. The safety belt web of claim. 6 wherein said first threads areselected from the class consisting of polyester fibers, polyvinylalcohol fibers, cotton, metallic threads and combinations thereof.

8. The safety belt of claim 1 wherein said first threads extendsubstantially linearly and said second threads are of undulateconfiguration.

9. A safety belt web comprising upper and lower longitudinally extendingtransversely spaced warps, a filler interwoven alternately withsuccessive upper and lower groups of said warps and transferring atspaced intervals between said upper and lower warps to form upper andlower weaves which delineated in said web a plurality of longitudinallyextending passageways transversely separated by said filler along thelongitudinal lines of the transfer points thereof, and core threadsextending longitudinally in said passageways, said core threads havingless elongation versus load and less weave crimp than said warps and atleast some of said core threads having elongations different from otherof web loading of about 500 kilograms.

1. A woven energy absorbing safety belt web comprising first and secondgroups of warp threads of relatively low and relatively high elongationrespectively, and a filler thread interwoven with said warp threads,said second group warp threads having a weave crimp exceeding that ofsaid first group warp threads and said first group warp threadscomprising a plurality of core threads having elongations different fromeach other and lower than that of said second group warp threads, andsaid first group warp threads having a non-recoverable extensibilityunder a substantially constant predetermined load for a predeterminedelongation before the rupture of said first group warp threads ofmaximum elongation.
 2. The safety belt web of claim 1 wherein saidsecond relatively high elongation warp threads are disposed outwardly ofsaid first low elongation warp threads relative to the opposite outerfaces of said web.
 3. The safety belt web of claim 1 wherein said firstwarp threads are under tension relative to said second warp threads whensaid web is in an overall relaxed condition.
 4. The safety belt web ofclaim 1 wherein said first warp threads of maximum elongation extendssubstantially linearly between said filler threads disposed alongopposite sides of said first warp threads and said second warp threadsinterweave said filler threads and are disposed along opposite faces ofsaid web.
 5. The safety belt web of claim 1 wherein said first threadshave a rupture elongation of 20 percent and at a total load on said webof about 500 kilograms.
 6. The safety belt web of claim 1 wherein saidsecond threads comprise nylon.
 7. The safety belt web of claim 6 whereinsaid first threads are selected from the class consisting of polyesterfibers, polyvinyl alcohol fibers, cotton, metallic threads andcombinations thereof.
 8. The safety belt of claim 1 wherein said firstthreads extend substantially linearly and said second threads are ofundulate configuration.
 9. A safety belt web comprising upper and lowerlongitudinally extending transversely spaced warps, a filler interwovenalternately with successive upper and lower groups of said warps andtransferring at spaced intervals between said upper and lower warps toform upper and lower weaves which delineated in said web a plurality oflongitudinally extending passageways transversely separated by saidfiller along the longitudinal lines of the transfer points thereof, andcore threads extending longitudinally in said passageways, said corethreads having less elongation versus load and less weave crimp thansaid warps and at least some of said core threads having elongationsdifferent from other of said core threads, and said core threads havinga non-recoverable extensibility under a substantially constantpredetermined load for a predetermined elongation before the rupture ofsaid core threads of maximum elongation.
 10. The web of claim 9 whereina plurality of said core threads is disposed in each of saidpassageways.
 11. The web of claim 9 wherein said core threads aresubstantially linear.
 12. The web of claim 9 wherein said core threadshave a rupture elongation of about 20 percent at a total web loading ofabout 500 kilograms.